Generation of electrospun nanofibers with controllable degrees of crimping through a simple, plasticizer-based treatment

Abstract

Electrospun nanofibers with controllable degrees of crimping are fabricated by simply exposing the samples to a plasticizer at preset shrinkage ratios. Compared with their straight counterparts, the crimped nanofibers are able to mechanically mimic native tendon tissue and better protect tendon fibroblasts under uniaxial strains.

Keywords: crimping; electrospun nanofibers; plasticizer; scaffold; tendon tissue engineering.

Figure 1

A schematic illustration of the procedure for generating nanofibers with controllable degrees of crimping. The initial length of the strip was defined as L₀ while the distance between the two ends after ethanol treatment was denoted as L. For L=L₀, the strips were treated with the two ends fixed at a distance equal to the original length. When L<L₀, the strip initially at slack would shrink to a length of L during ethanol treatment.

Figure 2

SEM images showing (A) the pristine PLA nanofibers, (B–E) the same batch of PLA nanofibers after treating with ethanol at L/L₀= (B) 100%, (C) 75%, (D) 50%, and (E) 25%. The degree of crimping was found to depend on the value of L/L₀. (F) Plot showing the relationship between wavelength/amplitude of the crimps and L/L₀. The wavelength showed a positively correlation with the value of L/L₀ while the amplitude of the crimp remained essentially the same. (G) Plot showing the relationship between the diameter of crimped fibers and L/L₀. The diameter was negatively correlated with the value of L/L₀. Roughly one hundred fibers were randomly selected from each sample for analysis, and the data are presented as mean ± standard deviation.

Figure 3

Representative Raman spectra (A) and DSC curves (B) of the pristine PLA nanofibers (sample-a) and the samples treated at L/L₀=50% (b) and L/L₀=100% (c), respectively. The box in (A) indicates the Raman peaks sensitive to the conformation of polymer chains.

Figure 4

A comparison of the tensile mechanical tests involving (A) stress-strain behavior, (B) Young’s modulus, (C) yield strain, (D) toughness, and (E) ultimate stress for the pristine PLA nanofibers and those treated at L/L₀=50% and L/L₀=100%, respectively. N = 12 for each group; the data are presented as mean ± standard deviation; the * above the bars indicates significant difference as compared with the pristine nanofibers (p<0.05).

Figure 5

Live/dead staining of TFBs cultured on (A–C) pristine and (D–F) L/L₀=50% crimped PLA nanofibers. TFBs in (B) and (E) subjected to 10% strain, while those in (C) and (F) subjected to 20% strain. The arrow in (A) indicates the alignment of the nanofibers and the direction of uniaxial strain externally applied.